currently if skb does not have enough headroom skb_realloc_headrom is called.
It is not optimal because it creates new skb.
Unlike skb_realloc_headroom, new helper skb_учзфтв_head
does not allocate a new skb if possible;
copies skb->sk on new skb when as needed
and frees original skb in case of failures.
This helps to simplify ip[6]_finish_output2(), ip6_xmit() and a few other
functions in vrf, ax25 and bpf.
There are few other cases where this helper can be used but they require
an additional investigations.
v2 changes:
- helper's name was changed to skb_expand_head
- fixed few mistakes inside skb_expand_head():
skb_set_owner_w should set sk on nskb
kfree was replaced by kfree_skb()
improved warning message
- added minor refactoring in changed functions in vrf and bpf patches
- removed kfree_skb() in ax25_rt_build_path caller ax25_ip_xmit
NB: patch "ipv6: use skb_expand_head in ip6_finish_output2" depends on
patch "ipv6: allocate enough headroom in ip6_finish_output2()" submitted separately
https://lkml.org/lkml/2021/7/12/732
Vasily Averin (7):
skbuff: introduce skb_expand_head()
ipv6: use skb_expand_head in ip6_finish_output2
ipv6: use skb_expand_head in ip6_xmit refactoring
ipv4: use skb_expand_head in ip_finish_output2
vrf: use skb_expand_head in vrf_finish_output
ax25: use skb_expand_head
bpf: use skb_expand_head in bpf_out_neigh_v4/6
drivers/net/vrf.c | 21 +++++---------
include/linux/skbuff.h | 1 +
net/ax25/ax25_out.c | 12 ++------
net/ax25/ax25_route.c | 13 ++-------
net/core/filter.c | 27 ++++-------------
net/core/skbuff.c | 42 +++++++++++++++++++++++++++
net/ipv4/ip_output.c | 13 ++-------
net/ipv6/ip6_output.c | 78 +++++++++++++++++---------------------------------
8 files changed, 90 insertions(+), 117 deletions(-)
--
1.8.3.1
